Yeah that’s exactly right! You have the proxy listen on 80/443 and use the subdomains to proxy to the respective other services that you have listen to other ports. Make sure those other ports are not open to the outside, though, as that would allow someone to bypass the proxy. In you example, you would change away from 0.0.0.0 to 127.0.0.1, which means the port is only open to the loop back interface, not the other ones. This happens accidentally especially when using docker for the app service. Also you should probably run some firewall to block all ports that you don’t wish to expose.

I’d really suggest you take a look at Caddy for the reverse proxy. It completely handles SSL certificate creation and renewal so you don’t have to do anything.

You can already do that without a reverse proxy.

A reverse proxy allows you to have multiple services running on 0.0.0.0:XXXA

For example you might have two websites at a server on 192.168.0.123

Your server will be setup to show those websites at two different ports, say "192.168.0.123:123" and "192.168.0.123:321" - with foo.com on 123 and example.net at 321

Your reverse proxy will listen to requests on port 80 (where websites are usually served) and look at each request. If it's a request for the website at foo.com, it'll send it to port 123. If it's a request for example.net it will send it to port 321

But the client who is requesting the sites will only see port 80, at the same IP address for both sites.